JP6025741B2 - Additives for dye-sensitized solar cells - Google Patents

Description

  The present invention relates to at least one tertiary amine-N-oxide of formula I as an additive in dye-sensitized solar cells (DSSC) and all tautomers or stereoisomers corresponding to such formula I. It relates to the use of body forms as well as to special electrolyte formulations and dye-sensitized solar cells comprising at least one compound of the formula I.

  Dye-sensitized solar cells using sensitizing dyes have attracted widespread attention. A dye-sensitized solar cell includes, for example, a transparent conductive film formed in this order on a transparent substrate, a porous semiconductor electrode having a sensitizing dye supported therein, a hole transport layer, and a counter electrode including.

Examples of such cells are described in the literature: O'Regan, B. and Graetzel, M. (1991) Nature, 353, 737. The solar cell in this case contains a pair of counter electrodes (anode and cathode) and an electrolyte between them. The electrolyte includes iodide ion pairs having different oxidation states as a hole medium created upon charge separation at the dye-sensitized nanoporous semiconductor-electrolyte interface. The cathode is made of a conductive material, while the anode is a plate of transparent material, such as glass, on which the transparent conductivity of light transmissive tin dioxide (SnO ₂ ) that can be doped with other elements. Made from said plate having a layer as well as a semiconductor titanium dioxide (TiO ₂ ) layer thereon. The TiO ₂ layer is formed of a TiO ₂ semiconductor composed of nanocrystalline particles to which a sensitizing dye is bonded. When the interface between the TiO ₂ nanocrystal layer and the dye is illuminated, electrons are injected into TiO ₂ .

On the other hand, the medium undergoes oxidation in the electrolyte; three iodide ions (I ⁻ ) emit two electrons, resulting in triiodide ions (I ₃ ⁻ ) with a high degree of oxidation. The electrons are then transported through the TiO ₂ nanocrystal layer and collected by the transparent conductive layer while the triiodide ion (I ₃ ⁻ ) diffuses to the cathode and acquires two electrons to obtain iodine. Reduced to fluoride ion (I ⁻ ). In this way, this type of wet cell converts solar energy into electrical energy.

  Dye-sensitized solar cells have been expected to be useful as solar cells for the next generation because of their simple and convenient manufacturing methods and hence reduced material costs.

In order to put dye-sensitized solar cells into practical use, there is a need for further improvements in conversion efficiency, and for that reason, the current generated (short circuit current, J _sc ), in open circuit voltage (V _OC ), and There was a need for an increase in safety and durability.

  The best-functioning dye-sensitized solar cells now contain at least one volatile organic solvent, reducing the viscosity of the electrolyte and thus increasing the ion mobility. The biggest problem here is that, as disclosed in, for example, Yu Bai et al., “High-performance dye-sensitized solar cells based on solvent-free electrolytes produced from eutectic melts”, Nature Materials 2008, 1, For the purpose of being composed solely of ions, the volatility of the electrolyte is removed or reduced by replacing the volatile solvent with an ionic liquid.

One of the factors limiting the power conversion efficiency of DSCCs based on ionic liquids is the injected electrons or conduction bands in the semiconductor due to a fairly large amount of oxidized sites of the redox couple (eg, I ₃ ⁻ ) in the relevant operating state It can be a fairly large recombination of electrons (eg TiO ₂ ). In order to increase the open circuit voltage, it is necessary to avoid such recombination, in other words, to suppress leakage current at the semiconductor electrolyte junction.

The leakage current occurs above the reduction of triiodide by conduction band electrons (e ⁻ _cb ), which occurs despite the TiO ₂ surface being coated with a single layer of dye:
I ₃ ⁻ + 2e ⁻ _cb (TiO ₂ ) → 3I ⁻
Arising from. Since triiodide is relatively small in size, it can cross the dye layer or the dye cannot be completely covered, ie the surface of TiO ₂ is bare and exposed to the redox electrolyte Either have access to a hole of size.

Recombination is typically suppressed by the addition of compounds that are adapted to free sites on the TiO ₂ surface and are therefore thought to prevent access to possible recombination sites for triiodide or free iodine. The Examples of compounds typically used for this purpose are (poly) ether derivatives, amides, esters, nitriles. The current best result is that N-alkyl-benzimidazole (Zhaofu Fei et al., Inorg. Chem. 2006, 45, 10407-10409, A Supercooled Imidazolium Iodide Ion Liquid as a Low-Viscosity Electrolyte for Dye-Sensitized Solar Cells ), 4-tert-butylpyridine (TBP, MK Nazeeruddin et al., J. Am. Chem. Soc. 1993, 115, 6382-6390) or nitrogen-containing complexes such as tetrazole, pyrazole, triazole, pyrazine, pyrimidine, triazine It has been achieved using ring additives (H. Kusama et al., J. Photochem. Photobiol., A Chemistry, 2005, 169-176). TBP and nitrogen-containing heterocyclic additives are believed to be particularly useful in electrolytes comprising at least one volatile organic solvent.

The donating properties of nitrogen lone pairs in known heterocyclic additives to date are believed to be responsible for enhanced V _OC .

  US 2005/0150544 is a Ruthenium 535-bis TBA dye, the dye used is manufactured by Solaronix Col, Swiss, and a heterocyclic compound in which the electrolyte solution based on acetonitrile contains oxygen atoms in the ring, such as tetrahydrofuran, 2-methyl-tetrahydrofuran, pyran, tetrahydropyran, furan, 2-methyl-furan, 1,4-dioxane, trioxane, 4-methyl-1,3-dioxolane, 1,3-dioxolane, 1,3-dioxane, 2H -1,3-dioxole, 3H-1,2-dioxole, dioxene, 1,4-dioxin, trioxane and the like, and the concentration of the heterocyclic compound in the electrolyte solution is 5 to 40% by volume A solar cell is described.

  When TBP is used, contamination to the counter electrode is observed. Furthermore, TBP is volatile, which means that it affects the stability and durability of the device.

  When other heterocyclic additives are used, a significant drop in short circuit current is observed and the actual open circuit voltage obtained is low.

  However, a novel and improved open circuit voltage can be achieved by shifting the oxide semiconductor conduction band edge in the negative direction and / or by reducing leakage current and thus maximizing the maximum power operating voltage. There is a continuing need for improved additives. The open circuit voltage must be tailored to achieve improved DSC efficiency over a wide temperature range (ie, in the range of 40 ° C. to 120 ° C.), including temperatures above room temperature and well below the temperature at which pigmentation occurs. One important parameter.

The object of the present invention is therefore to induce a shift of the conduction band edge of porous semiconductors, preferably as an additive for dye-sensitized solar cells acting as recombination inhibitors, and / or preferably of TiO ₂ It is to provide alternative and / or improved compounds as agents that induce it.
Surprisingly, it has been found that special tertiary N-oxides satisfy such requirements.

The tertiary N-oxides of formula I are believed to act as recombination inhibitors and / or as agents that induce conduction band edge shifts in porous semiconductors and consequently increase open circuit voltage (V _oc ). ing. Therefore, the tertiary N-oxide represented by Formula I can act as an additive that can reduce leakage current and enhance the conduction band edge, both increasing V _OC .

Therefore, the present invention firstly provides the formula I

In which R ¹ , R ² and R ³ are independently of each other,
Straight-chain or branched alkyl having 1 to 20 C atoms, which can be substituted by at least one R;
An aryl having 6-10 C atoms, which can be substituted by at least one R;
Alternatively, R ¹ , R ² and R ³ are fused to give 1, 2 or 3 N atoms or 1 N atom and 1 S or 1 O atom, and at least one R Forming a heteroaromatic ring structure that can be substituted;
Alternatively, R ¹ and R ² are fused to give 1, 2 or 3 N atoms or 1 N atom and 1 S or 1 O atom and are substituted by at least one R Forming a heteroalicyclic structure, and R ³ is a linear or branched alkyl having 1 to 20 C atoms, or is condensed to contain at least one N atom tricyclic structure is formed, and wherein the second or third N atom of the heterocyclic alicyclic structure or tricyclic structure -O be ^- and linear or branched having 1 to 20 C atoms Optionally substituted by alkyl
and

R is independently, Hal, CN, C (O ) H, linear or branched alkyl having 1 to 20 C atoms, which the cycloalkyl having 5-6 C atoms or 6 Can be substituted by aryl having from 10 to 10 C atoms, wherein the aryl group is by a linear or branched alkyl or alkoxy group having from 1 to 4 C atoms or 5 or 6 substituted by heteroaryl having C atoms but it may also, linear or branched alkenyl having 2-20 C atoms, which is substituted by aryl having 6 to 10 C atoms Wherein the aryl group is optionally substituted by a linear or branched alkyl group having 1 to 4 C atoms, a cycloalkyl having 5 or 6 C atoms, 1 to Linear or branched hydroxyalkyl having 0 C atoms, linear or branched alkoxy having 1 to 20 C atoms, which is substituted by aryl having 6 to 10 C atoms Ru can have, 1-20 linear or branched alkylthio having C atoms, aryl having 6 to 10 C atoms, an wherein the aryl group is 1 to 4 C atoms it may be substituted by a heteroaryl having an alkyl group or an alkoxy group or branched linear or 5 or 6 C atoms with, heteroaryl having 5 to 10 C atoms, wherein the hetero N atoms of the aryl group -O ^- may be substituted by, arylthio having aryloxy, 6-10 C atoms having 6-10 C atoms, 1-20 C Hara A linear or branched alkyl or dialkylamino having,

Hal is F, Cl, Br or I.
And at least one tautomer or stereoisomer thereof as an additive in a dye-sensitized solar cell.

JP 2006/202646 refers to 4-phenyl-pyridine-N-oxide as a possible additive in the electrolyte for various devices such as lithium secondary batteries, electrolytic capacitors, electric double layer capacitors and the like. It is mentioned by chance that electrolytes containing additives according to JP 2006/202646 containing 4-phenyl-pyridine-N-oxide can demonstrate thermal resistance and no color change upon heating. There is no suggestion that tertiary N-oxides according to Formula I can be used advantageously in dye-sensitized solar cells and that they have the ability to increase V _OC .

  At least one compound according to formula I can be applied according to the invention as a component of the electrolyte, as a coadsorbent during dye application or by other methods. Preferably, at least one compound of the formula I is applied as an electrolyte component or as a coadsorbent, particularly preferably as an electrolyte component.

  The at least one compound of the formula I above can be used as a single additive or other known additives such as the (poly) ether derivatives, amides, esters, nitriles or heterocycles mentioned above It can be used in combination with a compound or the like.

  The type of electrolyte useful in a given device such as a dye-sensitized solar cell is not limited. The electrolyte may be based on molecular solvents or organic salts, commonly described as molten salts or ionic liquids. In electrolytes that do not contain highly volatile molecules such as low molecular organic solvents, it is preferred to use the N-oxides of formula I above.

  Linear or branched alkyl groups having 1 to 20 C atoms are for example methyl, ethyl, propyl, isopropyl, n-butyl, sec. -Butyl, tert. -Butyl, 1- (2,2-dimethyl) -propyl, pentyl, hexyl, heptyl, octyl, x-methylbutyl, where x is 1; 2 or 3, x-methylpentyl, where x is 1; 2; 3 or 4 and x-methylhexyl, where x is 1; 2; 3; 4 or 5, and x-ethylpentyl, where x is 1, 2 or 3, and x-ethylhexyl, Where x is 1; 2; 3 or 4, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl, n-octadecyl, n-nonadecyl and n-eicosyl, which can be substituted by at least one R as defined below.

  Aryl having 6 to 10 C atoms is an aromatic compound such as phenyl, naphthyl or anthracenyl, which can be substituted by at least one R as defined below. Preferably aryl is phenyl, which can be substituted by at least one R.

  Heteroaryl having 5 or 6 C atoms is, for example, 2- or 3-furyl, 2- or 3-thienyl, 1-, 2- or 3-pyrrolyl, 1-, 2-, 4- or 5- Imidazolyl, 3-, 4- or 5-pyrazolyl, 2-, 4- or 5-oxazolyl, 3-, 4- or 5-isoxazolyl, 2-, 4- or 5-thiazolyl, 3-, 4- or 5- Isothiazolyl, 2-, 3- or 4-pyridyl, 2-, 4-, 5- or 6-pyrimidinyl, 1,2,3-triazol-1-, -4- or -5-yl, 1,2,4 -Triazol-1-, -4- or -5-yl, 1- or 5-tetrazolyl, 1,2,3-oxadiazol-4- or -5-yl 1,2,4-oxadiazole-3 -Or -5-yl, 1,3,4- Asiazol-2- or -5-yl, 1,2,4-thiadiazol-3- or -5-yl, 1,2,3-thiadiazol-4- or -5-yl, 2-, 3-, 4 -, 5- or 6-2H-thiopyranyl, 2-, 3- or 4-4H-thiopyranyl, 3- or 4-pyridazinyl or pyrazinyl. Preferably heteroaryl is 2-, 3- or 4-pyridyl.

  Heteroaromatic ring structures in which 1, 2 or 3 N atoms are present, or 1 N and 1 S or 1 O atom are present, for example, pyrrole, imidazole, pyrazole, triazole, pyridine, pyridazine , Pyrimidine, pyrazine, thiazole, oxazole, indole, quinoline, quinoxaline or benzimidazole, which can be substituted by at least one R as defined below. Preferably, the heteroaromatic ring structure is pyridine, pyrazine, imidazole, benzimidazole or quinoline, which can be substituted by at least one R as defined below. Examples of compounds of formula I having a heteroaromatic ring structure useful according to the invention include those of formulas IIa, IIb, IIc, IId, IIe, IIf and IIg.

In which R ′ is independently H or R, R ′ ″ is independently H, linear or branched alkyl or alkoxy having 1 to 4 C atoms, or 5 or Heteroaryl having 6 C atoms, R ^* is independently H, linear or branched alkyl having 1 to 4 C atoms, and R ^x is independently H, Straight chain or branched alkyl having 1 to 20 C atoms, which is cycloalkyl having 5 to 6 C atoms or aryl having 6 to 10 C atoms, wherein the aryl group May be substituted by a linear or branched alkyl or alkoxy group having 1 to 4 C atoms or by a heteroaryl having 5 or 6 C atoms, and R is defined below It is represented by the compound of

  Heteroalicyclic structures in which 1, 2 or 3 N atoms or 1 N atom and 1 S atom or 1 O atom are present are, for example, pyrrolidine, imidazolidine, piperidine, piperazine, hexahydro-pyrimidine , Hexahydro-pyridazine, 1,3,5-triazinan, morpholine, thiomorpholine, oxazolidine, thiazolidine, which can be substituted by at least one R as defined below. Preferably, the heteroalicyclic structure is pyrrolidine, piperidine, morpholine, oxazolidine or hexahydropyridazine, which can be substituted by at least one R as defined below. Examples of compounds of formula I having such heteroalicyclic structures useful according to the invention are those of formula IIIa, IIIb or IIIc

Where X is CH ₂ , O or NR, R ″ is a straight or branched alkyl having 1 to 20 C atoms, R ′ is H or R, and R is Represented by the compounds defined below.

Heteroaliphatic tricyclic structures having at least one N atom are, for example, 1-aza-bicyclo [3.2.1] octane, 1-aza-bicyclo [2.2.2] octane, 1,4-diaza. -Bicyclo [2.2.2] octane, which can be substituted by at least one R as defined below. Examples of compounds of formula I having such a heteroaliphatic tricyclic structure are of formula IIId
Wherein Y is CH, N, N ⁺ R, N ⁺ O ⁻ , R ′ is H or R, and R is defined below.

R is independently, Hal, CN, C (O ) H, linear or branched alkyl having 1 to 20 C atoms, which the cycloalkyl having 5-6 C atoms or 6 It can be substituted by aryl having 10 C atoms, wherein the aryl group is 1-4 or by straight-chain or branched alkyl or alkoxy group having C atoms 5 or 6 substituted by heteroaryl having C atoms but it may also, linear or branched alkenyl having 2-20 C atoms, which is substituted by aryl having 6 to 10 C atoms Wherein the aryl group is optionally substituted by a linear or branched alkyl group having 1 to 4 C atoms, a cycloalkyl having 5 or 6 C atoms, 1 to Linear or branched hydroxyalkyl having 0 C atoms, linear or branched alkoxy having 1 to 20 C atoms, which is substituted by aryl having 6 to 10 C atoms Ru can have, 1-20 linear or branched alkylthio having C atoms, aryl having 6 to 10 C atoms, an wherein the aryl group is 1 to 4 C atoms but it may also be substituted by a heteroaryl having a linear or branched alkyl radical or or by an alkoxy group 5 or 6 C atoms with, heteroaryl having 5 to 10 C atoms, wherein said N atom of the heteroaryl group -O ^- but it may also be substituted by, arylthio having aryloxy, 6-10 C atoms having 6-10 C atoms, 1-20 C Hara A linear or branched alkyl or dialkylamino having, where Hal is F, Cl, Br or I.
Hal is preferably F, Cl or I.

  Optionally substituted by a linear or branched alkyl or alkoxy group having 1 to 4 C atoms, substituted by aryl having 6 to 10 C atoms, for example phenyl, naphthyl or anthracenyl A linear or branched alkyl group having 1 to 20 C atoms, which can be substituted by a heteroaryl having 5 or 6 C atoms as described above. , Described above as an example. Preferably, a linear or branched alkyl group substituted by aryl is benzyl, 1- (4-methoxy) -phenyl, 1- (4-methyl) -phenyl, 2-phenylethyl, 3-phenylpropoxy. 1- (2-phenyl) propyl, 4-phenylbutyl or 5-phenylpentyl, particularly preferably benzyl, 1- (4-methoxy) -phenyl, 3-phenylpropyl or 1- (2-phenyl) propyl is there.

The linear or branched alkyl group substituted by heteroaryl is preferably 1-pyridin-4-yl-methyl. In addition, N atom of the heteroaryl moiety is -O ^- may be replaced by.

  A straight-chain or branched alkyl group substituted by a cycloalkyl having 5 to 6 C atoms is preferably cyclopentyl-methyl, cyclopentyl-ethyl, cyclohexyl-methyl or cyclohexyl-ethyl.

  A straight-chain or branched alkoxy group having 1 to 20 C atoms is defined as O-alkyl, where alkyl is, for example, aryl having 6 to 10 C atoms, such as phenyl, naphthyl or anthracenyl. Methyl, ethyl, propyl, isopropyl, n-butyl, sec. -Butyl, tert. -Butyl, pentyl, hexyl, heptyl, octyl, x-methylbutyl where x is 1; 2 or 3; x-methylpentyl where x is 1; 2; 3 or 4; x is 1; 2; 3; 4 or X-methylhexyl which is 5, x-ethylpentyl where x is 1, 2 or 3; x-ethylhexyl where x is 1; 2; 3 or 4; nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl Hexadecyl, heptadecyl, octadecyl, nonadecyl and eicosyl. The straight-chain or branched alkoxy group substituted by aryl is preferably phenylmethoxy, phenylethoxy, phenylpropoxy or phenylbutoxy, particularly preferably phenylmethoxy.

  Cycloalkyl having 5 to 6 C atoms is cyclopentyl or cyclohexyl, preferably cyclohexyl.

  A linear or branched hydroxyalkyl group having 1 to 20 C atoms is a straight or branched chain having 1 to 20 C atoms, wherein at least one H is replaced by a hydroxy group It is an alkyl group.

  A straight-chain or branched alkylthio group having 1 to 20 C atoms is defined as S-alkyl, where alkyl is, for example, methyl, ethyl, propyl, isopropyl, n-butyl, sec. -Butyl, tert. -Butyl, pentyl, hexyl, heptyl, octyl, x-methylbutyl where x is 1; 2 or 3; x-methylpentyl where x is 1; 2; 3 or 4; x is 1; 2; 3; 4 or X-methylhexyl which is 5, x-ethylpentyl where x is 1, 2 or 3; x-ethylhexyl where x is 1; 2; 3 or 4; nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl Hexadecyl, heptadecyl, octadecyl, nonadecyl and eicosyl.

  An aryloxy group having 6 to 10 C atoms is defined as O-Aryl, where Aryl has the meaning defined above.

  Heteroaryl having 5-10 C atoms is, for example, 2- or 3-furyl, 2- or 3-thienyl, 1-, 2- or 3-pyrrolyl, 1-, 2-, 4- or 5- Imidazolyl, 3-, 4- or 5-pyrazolyl, 2-, 4- or 5-oxazolyl, 3-, 4- or 5-isoxazolyl, 2-, 4- or 5-thiazolyl, 3-, 4- or 5- Isothiazolyl, 2-, 3- or 4-pyridyl, 2-, 4-, 5- or 6-pyrimidinyl, more preferably 1,2,3-triazol-1-, -4- or -5-yl, 1, 2,4-triazol-1-, -4- or -5-yl, 1- or 5-tetrazolyl, 1,2,3-oxadiazol-4- or -5-yl 1,2,4-oxadi Azol-3- or -5-i 1,3,4-thiadiazol-2- or -5-yl, 1,2,4-thiadiazol-3- or -5-yl, 1,2,3-thiadiazol-4- or -5-yl, 2, -, 3-, 4-, 5- or 6-2H-thiopyranyl, 2-, 3- or 4-4H-thiopyranyl, 3- or 4-pyridazinyl, pyrazinyl, 2-, 3-, 4-, 5-, 6- or 7-benzofuryl, 2-, 3-, 4-, 5-, 6- or 7-benzothienyl, 1-, 2-, 3-, 4-, 5-, 6- or 7-1H-indolyl 1-, 2-, 4- or 5-benzimidazolyl, 1-, 3-, 4-, 5-, 6- or 7-benzopyrazolyl, 2-, 4-, 5-, 6- or 7-benzo Oxazolyl, 3-, 4-, 5-, 6- or 7-benzoisoxazolyl, 2- 4-, 5-, 6- or 7-benzothiazolyl, 2-, 4-, 5-, 6- or 7-benzoisothiazolyl, 4-, 5-, 6- or 7-benza-2,1, 3-oxadiazolyl, 1-, 2-, 3-, 4-, 5-, 6-, 7- or 8-quinolinyl, 1-, 3-, 4-, 5-, 6-, 7- or 8-isoquinolinyl, 1-, 2-, 3-, 4- or 9-carbazolyl, 1-, 2-, 3-, 4-, 5-, 6-, 7-, 8- or 9-acridinyl, 3- 4-, 5-, 6-, 7- or 8-cinnolinyl or 2-, 4-, 5-, 6-, 7- or 8-quinazolinyl.

In one preferred embodiment of the invention, wherein
R ¹ , R ² and R ³ independently of one another are linear or branched alkyl having 1 to 20 C atoms, preferably linear or branched having 1 to 9 C atoms Alkyl, particularly preferably methyl or nonyl, or
In which R ¹ , R ² and R ³ are condensed and can be substituted by at least one R, 1, 2 or 3 N atoms or 1 N and 1 S or Forms a heteroaromatic ring structure in which one O atom is present, preferably forms a heteroaromatic ring structure in which one or two N atoms are present, which can be substituted by at least one R. ,
Alternatively, R ¹ and R ² can be fused and substituted with at least one R, 1, 2 or 3 N atoms or 1 N atom and 1 S or 1 Forms a heteroalicyclic structure in which an O atom is present, and R ³ is a linear or branched alkyl having 1 to 20 C atoms, preferably R ¹ and R ² are condensed, 1 or 2 N atoms or 1 N atom and 1 O atom can be substituted by at least one R to form a heteroalicyclic structure, and R ³ is 1 Linear or branched alkyl having ˜4 C atoms,
Compounds of formula I, wherein R and R have the meanings defined above or have the preferred meanings defined below, can be used according to the present invention.

R is independently preferably straight-chain or branched alkyl having 1 to 20 C atoms, which is cycloalkyl having 5 to 6 C atoms or 6 to 10 C atoms aryl, wherein the aryl group may be substituted by a heteroaryl having a linear or branched alkyl group or by 5 or 6 C atoms having 1 to 4 C atoms, 2 to 20 Linear or branched alkenyl having 1 C atom, which can be substituted by aryl having 6 to 10 C atoms, wherein the aryl group contains 1 to 4 C atoms An aryl having 6 to 10 C atoms, optionally substituted by a linear or branched alkyl group having, wherein the aryl group is a linear or branched having 1 to 4 C atoms Alkyl group or The Kokishi group, or may be substituted by a heteroaryl having 5 or 6 C atoms, or a dialkylamino having 1 to 20 C atoms.

  R is independently particularly preferably straight-chain or branched alkyl having 1 to 20 C atoms, which is aryl having 6 to 10 C atoms or 1 to 20 C atoms. It can be substituted by linear or branched dialkylamino having.

  A dialkylamino having 1 to 20 C atoms is a dialkylamino group in which each alkyl group is a straight-chain or branched alkyl having 1 to 20 C atoms as defined above independently of each other Defined.

  Of the definitions of R, unsubstituted straight-chain or branched alkyl groups having 1 to 20 C atoms are preferably methyl, n-butyl, tert. -Butyl or 1- (2,2-dimethyl) -propyl.

  Within the definition of R, the dialkylamino group preferably has an alkyl group which is, independently of one another, straight-chain or branched alkyl having 1 to 4 C atoms, particularly preferably a methyl group.

  Preference is given to compounds of the formula IIa in which R ′ is located at the 4-position of the pyridine ring. R ′ is preferably H or R, wherein R is C (O) H, straight-chain or branched alkyl having 1 to 20 C atoms, which has 6 to 10 C atoms. Can be substituted by aryl, wherein the aryl group is substituted by a linear or branched alkyl or alkoxy group having 1 to 4 C atoms, 1-20 Linear or branched hydroxyalkyl having C atoms, linear or branched alkoxy having 1 to 20 C atoms, which is substituted by aryl having 6 to 10 C atoms Having the meaning of aryl having 6 to 10 C atoms or straight-chain or branched alkylamino or dialkylamino having 1 to 20 C atoms. R in formula II is preferably straight-chain or branched alkyl having 1 to 9 C atoms, which has 1 to 4 C atoms, which can be substituted by phenyl Linear or branched hydroxyalkyl, linear or branched alkoxy having 1 to 4 C atoms, which may be substituted by phenyl, phenyl or 1 to 4 C atoms It has a linear or branched dialkylamino. R in formula IIa is particularly preferably methyl, tert. -Butyl, dimethylamino, phenylpropyl, benzyloxy, phenyl or hydroxymethyl.

  Preference is given to compounds of the formula IIb in which the substituent R ′ is located at the 4, 5, 6 or 7 position of the quinoline ring. R ′ is preferably H or R, wherein R is substituted by straight or branched alkyl having 1 to 20 C atoms, which is substituted by aryl having 6 to 10 C atoms. Where the aryl is a straight chain having 1 to 20 C atoms, optionally substituted by a straight chain or branched alkyl group or alkoxy group having 1 to 4 C atoms. Or branched hydroxyalkyl, linear or branched alkoxy having 1 to 20 C atoms, which can be substituted by aryl having 6 to 10 C atoms, 6 to 10 It has the meaning of aryl having 1 C atom, or straight-chain or branched alkylamino or dialkylamino having 1 to 20 C atoms. Within formula IIb, R 'is preferably H.

In which R ′ is H and R ^x is independently H, straight or branched alkyl having 1 to 20 C atoms, which has 5 to 6 C atoms. By cycloalkyl or aryl having 6 to 10 C atoms, the aryl group can be substituted by a linear or branched alkyl or alkoxy group having 1 to 4 C atoms. Or compounds of formula IIc, which can be substituted by heteroaryl having 5 to 6 C atoms, are preferred . Within formula IIc, R ^x is preferably H, linear or branched alkyl having 1 to 9 C atoms, which can be substituted by cyclohexyl or phenyl, where the phenyl group is Which may be substituted by a linear or branched alkyl or alkoxy group having 1 to 4 C atoms; R ^x is particularly preferably H, methyl, tert. -Butyl, n-heptyl, phenylmethyl, methoxyphenylmethyl, 2-phenylpropyl or cyclohexylmethyl.

Wherein R ′ is preferably H or R, where R is substituted by straight or branched alkyl having 1 to 20 C atoms, which is substituted by aryl having 6 to 10 C atoms. Wherein the aryl group may be substituted by a linear or branched alkyl or alkoxy group having 1 to 4 C atoms and having 1 to 20 C atoms Straight-chain or branched hydroxyalkyl, straight-chain or branched alkoxy having 1 to 20 C atoms, which can be substituted by aryl having 6 to 10 C atoms, 6 Aryl having 10 C atoms or linear or branched alkylamino or dialkylamino having 1-20 C atoms, and R ^x is independently H, 1-20 C Have atoms Chain or branched alkyl, which is a cycloalkyl having 5 to 6 C atoms or an aryl having 6 to 10 C atoms, wherein the aryl group is a straight chain having 1 to 4 C atoms. A compound of formula IId, which may be substituted by a chain or branched alkyl or alkoxy group, or may be substituted by a heteroaryl having 5 or 6 C atoms Is preferred. Within formula IId, R ′ is preferably H. Within formula IId, R ^x is preferably H, linear or branched alkyl having 1 to 9 C atoms, which can be substituted by cyclohexyl or phenyl, where the phenyl group is Which may be substituted by a straight-chain or branched alkyl group having 1 to 4 C atoms or alkoxy; R ^x is particularly preferably H, methyl, tert. -Butyl, n-heptyl, phenylmethyl, methoxyphenylmethyl, 2-phenylpropyl or cyclohexylmethyl.

  Wherein R ′ is H and R ′ ″ is H, straight or branched alkyl or alkoxy having 1 to 4 C atoms or heteroaryl having 5 or 6 C atoms, Preference is given to compounds of the formula IIe. Within Formula IIe, R "" is preferably H, methyl, ethyl, tert. -Butyl, methoxy, ethoxy or pyridyl; R '' 'is particularly preferably H.

Preference is given to compounds of the formula IIf, in which R ′ is H and R ^* is independently H or straight-chain or branched alkyl having 1 to 4 C atoms. Within formula IIf, R ^* is preferably H, methyl, ethyl or tert. -Butyl: R ^* is particularly preferably H.

  Preference is given to compounds of the formula IIg in which R 'is H or R, where R has the meaning of straight-chain or branched alkyl having 1 to 20 C atoms. Within formula IIg, R 'is preferably H.

Wherein R ′ is H or R, wherein R has the meaning of a straight-chain or branched alkyl having 1 to 20 C atoms, X is CH ₂ , O or NR, and Preference is given to compounds of the formula IIIa in which R ″ is straight-chain or branched alkyl having 1 to 20 C atoms. Within Formula IIIa, R ′ is preferably H. Within formula IIIa, X is preferably O. Within formula IIIa, R ″ ′ is preferably methyl, ethyl, n-propyl or n-butyl; R ″ is particularly preferably methyl.

  Preference is given to compounds of the formula IIIb in which R 'is H and R "is independently straight-chain or branched alkyl having 1 to 20 C atoms. Within formula IIIb, R ″ is preferably independently methyl, ethyl, n-propyl or n-butyl; R ″ is particularly preferably methyl.

  In which R ′ is H or R, wherein R has the meaning of straight-chain or branched alkyl having 1 to 20 C atoms, and R ″ is 1 to 20 C atoms. Preference is given to compounds of the formula IIIc which are straight-chain or branched alkyl having the formula Within Formula IIIc, R 'is preferably H. Within formula IIIc, R ″ is preferably methyl, ethyl, n-propyl or n-butyl; R ″ is particularly preferably methyl.

Wherein R ′ is H or R, wherein R has the meaning of linear or branched alkyl having 1 to 20 C atoms, and Y is CH, N, N ⁺ R or N ⁺ -O ^- a compound of formula IIId are preferred. Within formula IIId, R ′ is preferably H. In the formula IIId, Y is preferably CH, N or ^N + -O ^- a.

  Of the compounds of formulas IIa, IIb, IIc, IId, IIe, IIf, IIg, IIIa, IIIb, IIIc and IIId as preferred compounds for the compounds of formula I described above, of formula IIa, Compounds represented by IIc, IId and IIIa are particularly preferred, and compounds represented by formulas IIa, IId and IIIa are very particularly preferred.

Compounds of formula I include the following groups of compounds such as pyridine-N-oxide, 4-methyl-pyridine-N-oxide, 4-tert. -Butyl-pyridine-N-oxide, 4- (dimethylamino) pyridine-N-oxide, N-methyl-morpholine-N-oxide, 4- (1-phenylpropyl) -pyridine-N-oxide, 4- (phenyl) Methoxy) pyridine-N-oxide, pyrazine-N-oxide, 4- (phenyl) -pyridine-N-oxide, 4- (hydroxymethyl) -pyridine-N-oxide, 4- (formyl) -pyridine-N-oxide , Trimethylamino-N-oxide, dimethyl-nonyl-amine-N-oxide, Nn-butyl-benzimidazole-3-oxide, N-benzyl-benzimidazole-3-oxide, N-[(4-methoxyphenyl ) Methyl] -benzimidazole-3-oxide, N- (2-phenylpropyl) -benzimidazo Ru-3-oxide, N-[(2 ′, 2′-dimethyl) propi)]-benzimidazole-3-oxide, N- (cyclohexylmethyl) -benzimidazole-3-oxide or Nn-heptyl-benz It is represented by imidazole-3-oxide or the like.

The present invention further relates to at least one compound of the formula I described above or preferably described as redox active species, such as iodide / triiodide, or Co (II) / Co (III ) Complex pairs such as Co (II) / Co (III) (dbbip) ₂ , where dbbip means 2,6-bis (1′-butylbenzimidazol-2′-yl) pyridine, Co (II ) / Co (III) (bpy) ₃ where bpy represents bipyridine or an alkylated bipyridine derivative thereof, etc., and the counter anion includes perchlorate, fluoroperfluoroalkyl phosphate, eg perfluoroethyl Pentafluorophosphate or the like, or (fluoro) cyanoborate, especially tetracyanoborate, preferably It is a redox pair of iodide and at least one iodide salt. This electrolyte formulation can be used as an electrolyte in a dye-sensitized solar cell.

It is is is or wherein preferably described above, the electrolyte formulation according to the invention containing the additives of the invention is a substitute or improvements therein to the known electrolyte formulations in the field of the electrolyte formulation for a dye-sensitized solar cell There is . When using the additives of the present invention, such electrolyte formulations exhibit comparable or increased power conversion efficiency and avoid the disadvantages of current known additives such as tert-butyl-pyridine. The additive of the invention of formula I described above or preferably described increases the open circuit voltage (V _oc ) and hence the power conversion efficiency of the dye-sensitized solar cell as defined above Let

In chemistry, an electrolyte is any substance that contains free ions that make the substance conductive. The most typical electrolyte is an ionic solution, but molten and solid electrolytes are also possible.
Therefore, the electrolyte formulation according to the present invention is basically a conductive medium because of the presence of at least one substance present in the dissolved or molten state, ie it supports conductivity through the movement of ionic species. However, such conductivity may not be highly relevant to the electrolyte role of dye-sensitized solar cells. Therefore, the scope of the present invention is not limited to highly conductive electrolyte media.

  The term electrolyte can be used for an electrolyte formulation term that fully includes all of the ingredients disclosed for the electrolyte formulation.

  The at least one compound of formula I described above or preferably described is typically 0.01 to 30% by weight (% w / w), preferably 0, in the electrolyte formulation. Used at a concentration in the range of 1 to 20% by weight, more preferably 1 to 10% by weight.

Typical molar concentrations are 0.8-10M, preferably 2-5M. This molar concentration in the electrolyte can be achieved with one or more compounds of formula I as described above or preferably described.
For the purposes of the present invention, molarity refers to the concentration at 25 ° C.

The electrolyte formulation of the present invention contains iodine (I ₂ ). Preferably, it is 0.01 to 50 wt%, more preferably 0.1 to 20 wt%, and most preferably from 1 to 10% by weight of _{I 2.}

Iodide salt, I as inorganic or organic cations and anions ^- consists. There is no limitation on the type of cation. However, to limit the amount of different cations in the electrolyte formulation, especially for DSC, organic cations, eg organic compounds containing quaternary nitrogen atoms, preferably cyclic organic cations such as pyridinium, imidazolium, triazolium, pyrrolidinium or morpholinium Organic compounds containing can be used.

Preferably, the electrolyte formulation is a group of organic cations independently.
In which the substituents R ^{2 ′} and R ^{3 ′} each independently represent H or straight-chain or branched alkyl having 1 to 20 C atoms,
R ^{1 ′} and R ^{4 ′} are each independently of each other,
Linear or branched alkyl having 1 to 20 C atoms, which may optionally be partially fluorinated or perfluorinated,
A linear or branched alkenyl having 2 to 20 C atoms and one or more double bonds, which may optionally be partially fluorinated,
A straight-chain or branched alkynyl having 2 to 20 C atoms and one or more triple bonds, which may optionally be partially fluorinated,
Showing,
At least one iodide salt selected from:

  Particularly preferred examples of at least one iodide salt are 1-ethyl-3-methylimidazolium iodide (emim I), 1-propyl-3-methylimidazolium iodide (pmim I), 1-butyl-3 -Methyl-imidazolium iodide (bmim I), 1-hexyl-3-methylimidazolium iodide (hmim I), 1,3-dimethyl-imidazolium iodide (mmim I), 1-allyl-3-methyl It is imidazolium iodide (amim I), N-butyl-N-methyl-pyrrolidinium iodide (bmpl I) or N, N-dimethyl-pyrrolidinium iodide (mmpl I).

  Another component of the electrolyte formulation is one or several additional salts or solvents or additives as further indicated below.

  When the electrolyte formulation comprising the additive of the invention of formula I, described previously or preferably described, is a two-component system, it consists of the two salts described above, one further Salt and one iodide salt. When the electrolyte formulation is a ternary system, it contains two additional salts and iodide salts as described above or one additional salt and two iodide salts. The two component system is 90-20% by weight, preferably 70-25% by weight, more preferably 55-35% by weight of additional salt and 10-80% by weight, preferably 30-75% by weight, as described above. Or more preferably, it contains 45 to 65% by weight iodide salt. The percentages in this paragraph are expressed in terms of the total salt (= 100% by weight) present in the electrolyte formulation of the present invention.

  The amounts of further optional components (additives) shown below, such as N-containing compounds having unshared electron pairs, solvents, polymers, and nanoparticles are not considered there. The same percentage applies to ternary or quaternary systems, which means that the sum of the additional salts must be used in a certain range, for example two additional ionic liquids are present in the electrolyte formulation of the invention. In, for example, 90 to 20% by weight.

According to another aspect of the present invention, the electrolyte formulation comprises an organic cation and halide ion containing quaternary nitrogen, such as F ⁻ , Cl ⁻ , I ⁻ , polyhalide ion, fluoroalkanesulfonate, fluoroalkanecarboxyl. , Tri (fluoroalkylsulfonyl) methide, bis (fluoroalkylsulfonyl) imide, bis (fluorosulfonyl) imide, nitrate, hexafluorophosphoric acid, tris-, bis- and mono- (fluoroalkyl) fluorophosphate, tetra At least one further salt with an anion selected from fluoroborate, dicyanamide, tricyanomethide, tetracyanoborate, thiocyanate, alkylsulfonate or alkylsulfate is added to a fluorine having 1 to 20 C atoms. Oroarukan, preferably a perfluorinated, containing with alkyl having fluoroalkyl and 1-20 C atoms with 1 to 20 C atoms. The fluoroalkane or fluoroalkyl is preferably perfluorinated.

  Preferably, the further salt is selected from salts containing anions such as thiocinate or tetracyanoborate, a particularly preferred further salt is tetracyanoborate.

The cation of at least one further salt or a preferred further salt is selected among organic compounds containing quaternary nitrogen atoms, preferably cyclic organic cations such as pyrrolidinium, imidazolium, triazolium, pyrrolidinium or morpholinium.
In another embodiment of the present invention, a guanidine salt may be added to the electrolyte formulation of the present invention.

The following combinations of iodide salts and further salts, sometimes characterized as ionic liquids, are preferred:
a) pmim I and emim TCB (1-propyl-3-methylimidazolium iodide and 1-ethyl-3-methylimidazolium tetracyanoborate)
b) pmim I, guanidine thiocyanate and emim TCB
c) mmim I, emim I and emim TCB
d) mmim I, emimI guanidine thiocyanate and emim TCB
e) mmim I, pmimI, guanidine thiocyanate and emim TCB
f) mmim I, amimI, guanidine thiocyanate and emim TCB

  The electrolyte formulation of the present invention contains at least one nitrogen atom having an unshared electron pair as a further additive in addition to the compound of the present invention of formula I as described or preferably described above. Seed compounds, or tert. -Butyl-pyridine may also be included. Examples of such compounds can be found in EP 0 986 079 A2, starting on page 2, line 40-55, and again extending from page 3, line 14 to page 7, line 54, explicitly referred to Are incorporated herein by reference. Preferred examples of compounds having unshared electron pairs include imidazole and its derivatives, in particular benzimidazole and its derivatives.

  The electrolyte formulation of the present invention may include an organic solvent. Preferably, the electrolyte formulation of the present invention comprises less than 50% organic solvent. Particularly preferably, the electrolyte formulation comprises less than 40%, more preferably less than 30%, even more preferably less than 20% and even more preferably less than 10%. Most preferably, the electrolyte formulation comprises less than 5% organic solvent. For example, it is substantially free of organic solvents. Percentages are given based on weight percent.

  Organic solvents may be selected from those disclosed in the literature when present in such amounts as indicated above. Preferably, the solvent, if present, is propylene carbonate, ethylene carbonate, butylene carbonate, γ-butyllactone, γ-valerolactone, glutaronitrile, adiponitrile, N-methyloxazolidinone, N-methylpyrrolidinone, N, N '-Dimethylimidazolidinone, N, N-dimethylacetamide, cyclic urea, preferably 1,3-dimethyl-2-imidazolidinone or 1,3-dimethyl-3,4,5,6-tetrahydro-2 (1H ) -Pyrimidinone, glymes, preferably tetraglyme, sulfolane, such as 2-ethanesulfonyl-propane, 1-ethanesulfonyl-2-methyl-propane or 2- (propane-2-sulfonyl) -butane, preferably asymmetrically Substituted sulfones, 3-methyl sulfolane, dimethyl sulfo Such as xoxides, trimethyl phosphates and methoxy substituted nitriles have boiling points higher than 160 ° C, more preferably higher than 190 ° C. Other useful solvents are acetonitrile, benzonitrile and / or valeronitrile.

  If a solvent is present in the electrolyte formulation, it may further include a polymer as a gelling agent, where the polymer is polyvinylidene fluoride, polyvinylidene-hexafluoropropylene, polyvinylidene-hexafluoropropylene- They are chlorotrifluoroethylene copolymer, Nafion, polyylene oxide, polymethyl methacrylate, polyacrylonitrile, polypropylene, polystyrene, polybutadiene, polyethylene glycol, polyvinyl pyrrolidone, polyaniline, polypyrrole, and polythiophene. The purpose of adding these polymers to the electrolyte formulation is to make the liquid electrolyte a quasi-solid or solid electrolyte, thus improving the solvent residue, especially over time.

Formulations of the present invention, for _{example, SiO 2, TiO 2, Al} 2 O 3, MgO or may comprise a metal oxide such as further ZnO, they also increase the solidity and thus solvent residues it can.

The invention therefore further relates to the use of the electrolyte formulations described in detail above in dye-sensitized solar cells.
The invention therefore further relates to a dye-sensitized solar cell comprising at least one compound of the formula I as described or preferably described herein.

  In one preferred embodiment of the present invention, at least one compound of formula I is contained in the electrolyte solution, or in other words, at least one compound of formula I is part of the electrolyte formulation. The dye-sensitized solar cell described above.

  In dye-sensitized solar cells, the dye is used to convert sunlight into electrical energy. As long as the LUMO energy state is slightly above the conduction band edge of the photoelectrode to be sensitized, there is no limit on the choice of dye itself. Examples of dyes are disclosed in EP 0 986 079 A2, EP 1 180 774 A2 or EP 1 507 307 A1.

Preferred dyes are MK-1, MK-2 or MK-3 (its structure is described in FIG. 1 of N. Koumura et al, J. Am. Chem. Soc. Vol 128, no. 44, 2006, 14256-14257. )
D102 (CAS number 652145-28-3), D-149 (CAS number 786643-20-7), D205 (CAS number 936336-21-9), T. Bessho et al, Angew. Chem. Int. Ed. Vol. 49, 37, 6646-6649, 2010, YD-2, Y123 (CAS number 13112465-92-1), bipyridine-ruthenium dyes such as N3 (CAS number 141460-19-7), N719 (CAS number 207347). -46-4), Z907 (CAS number 502693-09-6), C101 (CAS number 1048964-93-7), C106 (CAS number 1152310-69-4), K19 (CAS number 847665-45-6) or Organic colors such as terpyridine-ruthenium dyes such as N749 (CAS number 359415-47-7) It is.

Particularly preferred dyes are Z907 or Z907Na or D205, both of which are amphiphilic ruthenium sensitizers. The dye Z907 means NaRu (2,2′-bipyridine-4-carboxylic acid 4′-carboxylate) (4,4′-dinonyl-2,2′-bipyridine) (NCS) ₂ .

The structure of D205 is
It is.
A very particularly preferred dye is Z907 or Z907Na.

  In a preferred embodiment, the dye is co-adsorbed with phosphinic acid. A preferred example of phosphinic acid is bis (3,3-dimethyl-butyl) -phosphonic acid (DINHOP) described in M. Wang et al, Dalton Trans., 2009, 10015-10020.

  For example, a dye-sensitized solar cell contains a photoelectrode, a counter electrode, and an electrolyte formulation or charge-carrying metal between the photoelectrode and the counter electrode, where the sensitizing dye faces the counter electrode Is absorbed on the surface of the photoelectrode on the side.

According to a preferred embodiment of the device according to the invention, it comprises a semiconductor, an electrolyte formulation as described above and a counter electrode.
According to a preferred embodiment of the present invention, the semiconductor comprises Si, TiO ₂ , SnO ₂ , Fe ₂ O ₃ , WO ₃ , ZnO, Nb ₂ O ₅ , CdS, ZnS, PbS, Bi ₂ S ₃ , CdSe, GaP, InP. , GaAs, CdTe, CuInS ₂ and / or based on a metal selected from the group of CuInSe ₂ . Preferably, the semiconductor has a mesoporous surface, thus increasing the surface optionally coated with the dye and in contact with the electrolyte. Preferably, the semiconductor is present on a glass support or plastic or metal foil. Preferably the support is conductive.

  The device of the present invention preferably includes a counter electrode. For example, glassy fluorine-doped tin oxide or tin-doped indium oxide (FTO glass or ITO glass, respectively) coated with Pt, preferably carbon, polyaniline or poly (3,4-ethylenedioxythiophene), which is a conductive allotrope (PEDOT). In addition to glass, metal substrates such as stainless steel or titanium sheets can be possible substrates.

  The device of the present invention can be produced as a corresponding device of the prior art by simply replacing the electrolyte with the electrolyte formulation of the present invention. For example, in the case of dye-sensitized solar cells, device assemblies are described in numerous patent literatures such as WO 91/16719 (eg 34 and 35) as well as scientific literature such as Barbe, CJ, Arendse, F., Comte. , P., Jirousek, M., Lenzmann, F., Shklover, V., Graetzel, MJ Am. Ceram. Soc. 1997, 80, 3157; and Wang, P., Zakeeruddin, SM, Comte, P., Charvet , R., Humphry-Baker, R., Graetzel, MJ Phys. Chem. B 2003, 107, 14336.

  Preferably, the sensitized semiconductor material serves as a photoanode. Preferably, the counter electrode is a cathode.

  The present invention provides a method for producing a photovoltaic cell comprising the steps of contacting an electrolyte formulation of the present invention with a surface of a semiconductor and optionally contacting the surface with a sensitizer. Preferably, the semiconductor is selected from the materials provided above, and the sensitizer is preferably selected from the quantum dots and / or dyes disclosed above, particularly preferably from the dyes.

  Preferably, the electrolyte formulation creates a vacuum on the internal lumen of the cell through the holes in the counter electrode, into a device that is purely purified on the semiconductor, or otherwise already includes a counter electrode. And it may be applied by adding electrolyte formulations disclosed in the references of Wang et al., J. Phys. Chem. B 2003, 107, 14336.

The present invention also provides compounds of formula IId
In which R ′ is H and R ^x is independently straight-chain or branched alkyl having 6-20 C atoms, or straight-chain having 1-20 C atoms or A branched alkyl, which is a cycloalkyl having 5 to 6 C atoms or an aryl having 6 to 10 C atoms, wherein the aryl group is a straight chain having 1 to 4 C atoms Can be substituted by a branched or branched alkyl or alkoxy group, or substituted by a heteroaryl having 5-6 C atoms, provided that phenylmethyl is excluded for R ^X Relates to the novel compounds represented. A novel compound of formula IId, wherein R ^x is preferably straight-chain or branched alkyl having 6 to 9 C atoms or methoxyphenylmethyl, 2-phenylpropyl or cyclohexylmethyl The compound is preferred.

The following novel compounds of the formula IId are particularly preferred:
N-[(4-methoxyphenyl) methyl] -benzimidazole-3-oxide, N- (2-phenylpropyl) -benzimidazole-3-oxide, N-[(2 ′, 2′-dimethyl) propyl)] Benzimidazole-3-oxide, N- (cyclohexylmethyl) -benzimidazole-3-oxide or Nn-heptyl-benzimidazole-3-oxide.

The invention therefore also relates to a process for the preparation of a compound of formula IId, in which a) alkylation of 2-nitroaniline is carried out
Where R ^x is as defined above,
And b) formylating the compound of formula IV to form intermediate V
Wherein R ^x is as defined above and then forms a compound of formula IId by a cyclization reaction.

Reaction of 2-bromonitrobenzene with R ^x —NH ₂ , where R ^x is as defined above, is an alternative to the described steps of a given process.
This alternative step may be carried out in an organic solvent or in the absence of an organic solvent if one starting material is liquid at a temperature between 10 ° C. and 200 ° C. at the reaction temperature. A preferred solvent is DMSO. A preferred reaction temperature is 80 ° C.

Step a) of the process is an alkylation reaction of 2-nitro-aniline with an alkyl aldehyde R ^x —CHO in the presence of acid, organic solvent and sodium triacetoxyborohydride. Such a reaction can be carried out at a temperature of 10 ° C to 40 ° C, preferably at room temperature. Preferably the acid is glacial acetic acid. Preferably, the organic solvent is dichloromethane.

All starting materials such as 2-bromonitrobenzene, alkylamine R ^x —NH ₂ , 2-nitro-aniline or alkyl aldehyde R ^x —CHO are commercially available.

The formylation of step b) is carried out at a temperature of 40-100 ° C., preferably at a reaction temperature of 70 ° C., of formula IV, wherein R ^x is as defined above and It can be carried out by the reaction of Alternatively, the compound of formula IV can be reacted with formic acid at a temperature between 150 ° C. and 200 ° C., preferably 160 ° C.

Cyclization is accomplished by addition of a solution of ammonium sulfide to a solution of aqueous ethanol and Formula V, where R ^x is as defined above, or borohydride to a suspension of palladium on charcoal in water. It can be carried out by addition of sodium and addition of a compound of formula V as defined above.
The reaction conditions for this type of reaction are well known in the industry. Exemplary reaction conditions are described in the experimental section below.

  Without further reference, it is assumed that one skilled in the art can utilize the above description in the broadest scope. The preferred embodiments and examples should therefore merely be considered as descriptive disclosure which is not fully limited in any way.

The synthesized compounds are characterized by NMR spectroscopy or elemental analysis. The NMR spectrum is measured in CDCl ₃ . Frequency used: ¹ H: 399.78 MHz and ¹³ C: 100.52 MHz, external standard: TMS for ¹ H and ¹³ C. ¹ H and ¹³ C NMR spectra were recorded on a JEOL JNM-LA3000 spectrometer. All spectra were recorded at ambient temperature.
Melting point experiments were performed on a METTLER TOLEDO FP90 Central Processor and FP81HT MBC Cell.

Experiment 1:
Synthesis of benzimidazole-N-oxide Benzimidazole N-oxide was prepared by the three-step synthesis shown in Scheme 1.

R in this reaction scheme is n-butyl for the synthesis of Nn-butyl-benzimidazole-3-oxide.
R in this reaction scheme is benzyl for the synthesis of N-benzyl-benzimidazole-3-oxide.
R in this reaction scheme is 4-methoxyphenylmethyl for the synthesis of N-[(4-methoxyphenyl) methyl] -benzimidazole-3-oxide.
R in this reaction scheme is 2-phenylpropyl for the synthesis of N- (2-phenylpropyl) benzimidazole-3-oxide.
R in this reaction scheme is 2 ′, 2′-dimethylpropyl for the synthesis of N-[(2 ′, 2′-dimethyl) propyl] -benzimidazole-3-oxide.
R in this reaction scheme is cyclohexylmethyl for the synthesis of N- (cyclohexylmethyl) -benzimidazole-3-oxide.
R in this reaction scheme is n-heptyl for the synthesis of Nn-heptyl-benzimidazole-3-oxide.

  R in this reaction scheme is the same as the term “alkyl” used in alkylamines or alkylaldehydes in the process description below.

1. Method A for N-alkylation of 2-nitroaniline :
2-Bromonitrobenzene (5 g, 24.75 mmol) and alkylamine (91.58 mmol) were dissolved in DMSO (50 mL), heated to 80 ° C. and stirred overnight. The reaction solution was then allowed to cool to room temperature before the addition of water (100 mL). The resulting solution was then extracted with toluene (3 × 50 mL) and the combined extracts were washed with brine (3 × 20 mL) and dried over MgSO ₄ . Filtration and evaporation gave nitrophenylamine.

Method B:
Sodium triacetoxyborohydride (17 g, 77.83 mmol) is added to a solution of 2-nitrobenzenamine (31.13 mmol), alkyl aldehyde (88.64 mmol), glacial acetic acid (10 mL), and dichloromethane (144 mL), and The reaction mixture was stirred at room temperature (48 h). Additional sodium triacetoxyborohydride (6.8 g, 31.13 mmol) was added and the solution was stirred at room temperature (24 h). The mixture was diluted with aqueous sodium bicarbonate (120 mL) and washed with AcOEt (4 × 120 mL). The combined organic phase was dried over MgSO4, filtered and the solvent removed in vacuo. The crude product was purified by distillation at 26.7 Pa.

2. Method A for N-formylation of 2- (N-alkyl) nitroaniline :
Formic acid (5.2 mL, 139.0 mmol) was added to a solution of N-substituted 2-nitroaniline (61.78 mmol) and acetic anhydride (26 mL, 278.0 mmol) and the reaction mixture was stirred at 70 ° C. for 9 h. . Acetic anhydride and formic acid were removed in vacuo and the crude product was purified by distillation at 26.7 Pa.

Method B:
2-Nitroaniline (5.59 g, 39.66 mmol) and formic acid (21.8 mL, 579.8 mmol) were placed in a 100 mL process vial equipped with a stir bar. The mixture was stirred at 160 ° C. (300 W) for 15 min. The reaction mixture was poured into water (100 mL), placed in an ice bath for 30 min, and the resulting precipitate was isolated by filtration, washed with water (30 mL) and dried at 50 ° C. overnight.

3. Cyclization method A:
A solution of ammonium sulfide ((NH ₄ ) ₂ S _(n) ) was added to a solution of aqueous EtOH (100 mL) and N-substituted 2′-nitroformanilide (5 g). After standing overnight at room temperature, the resulting brown solution was concentrated to about 10 mL by nitrogen gas bubbling under heating at 70 ° C. The precipitated sulfur was filtered off and washed with EtOH. After removal of EtOH from the combined filtrate and washing, diethyl ether was added to the residual oil. The resulting white crystals were collected by filtration and recrystallized from AcOEt / diethyl ether to give a white prism. The filtrate N-substituted benzimidazole was obtained.

Method B:
A solution of sodium borohydride (5.3 g, 129.6 mmol) in water (4.3 mL) is stirred into a suspension of palladium on charcoal (5%, 2.7 g) in water (36 mL). And slowly added. A solution of 2-nitroformanilide (8.97 g, 53.99 mmol) in pyridine (86.4 mL) was added to the mixture at a rate such that the temperature was maintained at 35-40 ° C. When the addition was complete (ca. 1 h), the mixture was stirred for an additional 15 min. The catalyst was filtered off and the filtrate was evaporated under reduced pressure. The residue is dissolved in water (ca. 70 mL), acidified (with conc. Hydrochloric acid), then concentrated to approximately half volume and again with aqueous ammonia before being evaporated to dryness under reduced pressure. I was sexualized. The residue is extracted with hot ethanol; when cooled, the extract is precipitated into an inorganic material, which is filtered off, and the filtrate is further concentrated and cooled to 1H-benzimidazole-3-oxide. Got.

Nn-butylbenzimidazole-3-oxide 4 (# 128)
Melting point 124.5 ° C
Yield 60%

N-benzylbenzimidazole-3-oxide 5 (# 137)
Melting point: 141.9 ° C
Yield 49%

N- (4-methoxyphenyl) methylbenzimidazole-3-oxide 6 (# 141)
Melting point 116.9 ° C
Yield 20%

N- (2-phenylpropyl) benzimidazole-3-oxide 7 (# 143: stereoisomeric mixture; major / minor = 2.17: 1)
Yield 36%

N- (2 ′, 2′-dimethyl) propylbenzimidazole-3-oxide 8 (# 147)
Melting point 111.3 ° C
Yield 51%

N- (cyclohexylmethyl) benzimidazole-3-oxide 9 (# 150)
Melting point 152.5 ° C
Yield 34%

Nn-heptylbenzimidazole-3-oxide 10 (# 196)
Melting point 70.8 ℃
Yield 55%

1H-benzimidazole-3-oxide 11 (# 200)
Melting point 217.7 ° C. (decomposed product) (literature value (lit.) 215 ° C., decomposed product)
Yield 13% (Method A), 7% (Method B)

Example 2: Formulations and Devices By using the benzimidazole N-oxide represented by Formula IId, the following electrolyte formulations are synthesized that demonstrate the unexpected benefits of electrolyte formulations.

  26% (w / w) 1,3-dimethylimidazolium iodide (mmimI), 28% (w / w) 1-ethyl-3-methylimidazolium iodide (emimI), 36% (w / w) ) 1-methyl-3-ethylimidazolium tetracyanoborate (emimTCB), 4% (w / w) iodine, and 6% (w / w) according to the invention, such as for example 1H-benzimidazole N-oxide An electrolyte formulation is prepared by mixing the electrolyte additive of formula IId of w). It may be necessary to apply heat below 60 ° C. to make the electrolyte formulation homogeneous.

The compounds mmimI, emimI, I ₂ and emimTCB are commercially available or known literature, such as Bonhote, P et al. Inorg. Chem. 1996, 35, 1168-1178, or tetracyanoboric acid Regarding the synthesis of an organic salt with a salt anion, it may be synthesized based on literature such as WO 2004/072089.

  Dye-sensitized solar cells are manufactured as disclosed in US 5,728,487 or WO 2007/093961:

A double layer, mesoporous TiO ₂ electrode is disclosed in Wang P. et al., J. Phys. Chem. B 2003, 107, 14336, in particular page 14337, in order to obtain a photoanode consisting of a double layer structure. Manufactured as follows. To produce the transparent nanoporous TiO ₂ electrodes, a screen printing paste containing nanoparticles of TiO ₂ anatase phase having a diameter of terpineol solvent and 20 to 30 nm, by using a hand printer in 5mm × 5mm square The shape was deposited on a conductive substrate. The paste was dried at 120 celsius for 10 minutes. Then another screen printing paste containing TiO ₂ with a diameter of 400 nm was deposited on top of the nanohard layer to produce an opaque phase.

The bilayer membrane was then sintered at 500 Celsius for 1 hour, resulting in a lower transparent layer (7 microns thick) and a top opaque phase (4 microns thick). After sintering, the electrode was immersed in a 40 mM aqueous solution of TiCl ₄ (Merck) for 30 minutes at 70 Celsius and then rinsed sufficiently quickly with pure water. The electrode thus treated with TiCl ₄ was dried for 30 minutes at 500 Celsius just prior to dye sensitization. The electrodes were soaked in acetonitrile (Merck HPLC grade) and tert-butyl alcohol (Merck), v: v = 1: 1 0.3 mM Z907 dye solution for 60 hours at 19 degrees Celsius. The counter electrode was made by pyrolysis as disclosed in the above reference. A drop of 5 mM solution of platinic acid (Merck) was dropped at 8 μl / cm 2 and dried on a conductive substrate. A dye-sensitized solar cell was assembled using a 30 micron thick Bynel (DuPont, USA) hot melt film and encapsulated by heat. The interior space was filled with each electrolyte formulation described herein to produce a corresponding device.

The dye Z907 is an amphiphilic ruthenium sensitizer Ru (2,2′-bipyridine 4,4′-dicarboxylic acid) (4,4′-dinonyl-2,2′-bipyridine) (NCS) ₂ or [Ru (H2dcbpy) (dnbpy) (NCS) ₂ ].

In order to obtain accurate light intensity, Air Mass 1.5 Global (AM1.5G) simulated sunlight is converted into Seigo Ito et al. “Calibration of solar simulator for evaluation of dye-sensitized solar cells” Solar Energy Materials & Solar Cells 82 ( 2004) 421 spectrally calibrated.
Measurement of the photocurrent-voltage curve is performed on a device placed on a black plate cooled to 25 ° C. under 1 Sun illumination. A 4 mm × 4 mm optical mask is placed on top of the manufactured device to define the light projection area.

  The energy conversion efficiency is generally the ratio between the effective output of the energy conversion device and the input of light illumination, and is determined by using an adjustable resistive load that optimizes the power output in the energy term.

The photovoltaic parameters thus obtained are summarized in Table 1. A control means no additive.

  In these measurements, 1H-benzimidazole N-oxide obtains higher efficiency than the additives N-butylbenzimidazole (NBB), benzimidazole (Benzizm) and N-methylbenzimidazole (NMB).

A dye-sensitized solar cell was produced according to the description in Example 2 using the electrolyte containing N-oxide in the table. Acetonitrile was used for the solvent.

The results are shown in Table 3.

These results indicate that V _OC and fill factor (FF) when 4-picoline N-oxide (synonymous with 4-methyl-pyridine-N-oxide) is included in the solvent-type electrolyte for dye-sensitized solar cells. Is shown to have increased.

Example 4:
A dye-sensitized solar cell was prepared as described in Example 2 using the electrolyte containing the N-oxide in Table 4.

The results are shown in Table 5.

These results indicate that when 4-picoline N-oxide is included in the ionic liquid electrolyte for dye-sensitized solar cells, V _OC and fill factor are increased.

Example 5:
Using the electrolyte containing N-oxide in Table 6, a dye-sensitized solar cell was manufactured.
The molar ratio of the electrolyte formulation is
mmim-I 36 / emim-I 36 / I2 5 / emim-TCB 48 / additive 2.

All N-oxides used here are commercially available.

Table 7 shows the results.

These results show that V _OC and fill factor increase when N-oxide substituents are shown in the chemical structure in ionic liquid electrolytes for dye-sensitized solar cells. As in Kusama's paper, not only the coupling constant, but also the dielectric constant of the additive can affect the increase in Voc.

Example 6:
Using the electrolyte containing N-oxide in Table 8, a dye-sensitized solar cell was manufactured. The molar ratio of the electrolyte formulation is
mmim-I 36 / emim-I 36 / I2 5 / emim-TCB 48 / additive in Table 2D-1.

The results are shown in Table 9.

These results show that in the ionic liquid electrolyte formulation for dye-sensitized solar cells, _VOC and fill factor increased with the exemplary N-oxide concentrations listed in Table 8.

Claims (14)

Formula I
In which R ¹ , R ² and R ³ are independently of each other,
Straight-chain or branched alkyl having 1 to 20 C atoms, which can be substituted by at least one R;
An aryl having 6-10 C atoms, which can be substituted by at least one R;
Alternatively, R ¹ , R ² and R ³ are one, two or three N atoms or one N atom and one S or one O atom, and are substituted by at least one R Forming a heteroaromatic ring structure with N atoms that can be
Alternatively, R ¹ and R ² may be substituted with at least one R, with 1, 2 or 3 N atoms or 1 N atom and 1 S or 1 O atom present Forming a possible heteroalicyclic structure with N atoms, and R ³ is a linear or branched alkyl having 1 to 20 C atoms, or condensed to contain at least one N atom tricyclic structure is formed, and wherein the second or third N atom of the heterocyclic alicyclic structure or tricyclic structure -O be ^- and linear or branched having 1 to 20 C atoms Optionally substituted by alkyl
And R are independently
Hal,
CN,
C (O) H,
Linear or branched alkyl having 1 to 20 C atoms, which is substituted by cycloalkyl having 5 to 6 C atoms or by aryl having 6 to 10 C atoms In which the aryl group may be substituted by a linear or branched alkyl or alkoxy group having 1 to 4 C atoms or by a heteroaryl having 5 or 6 C atoms,
Linear or branched alkenyl having 2 to 20 C atoms, which can be substituted by aryl having 6 to 10 C atoms, wherein the aryl group is 1 to 4 Optionally substituted by a linear or branched alkyl group having a C atom,
A cycloalkyl having 5 or 6 C atoms,
Linear or branched hydroxyalkyl having 1 to 20 C atoms,
Linear or branched alkoxy having 1 to 20 C atoms, which can be substituted by aryl having 6 to 10 C atoms,
Linear or branched alkylthio having 1 to 20 C atoms,
Aryl having 6 to 10 C atoms, wherein the aryl group is a straight chain or branched alkyl group or alkoxy group having 1 to 4 C atoms, or hetero having 5 or 6 C atoms Optionally substituted by aryl,
Heteroaryl having 5 to 10 C atoms, where the N atom of the heteroaryl group -O ^- may be substituted by,
Aryloxy having 6 to 10 C atoms,
Arylthio having 6 to 10 C atoms,
Linear or branched alkylamino or dialkylamino having 1 to 20 C atoms,
Hal is F, Cl, Br or I.
Or at least one tautomer or stereoisomer thereof as an additive to an electrolyte formulation in a dye-sensitized solar cell. Wherein R ¹ , R ² and R ³ in at least one compound of the formula I can be substituted by at least one R, 1, 2 or 3 N atoms or 1 Forming a heteroaromatic ring structure with N atoms in which one N and one S or one O atom are present, or R ¹ and R ² can be substituted by at least one R; Forming a heteroalicyclic structure with 1, 2 or 3 N atoms or 1 N atom and 1 S or 1 O atom together with N atoms, and R ³ is 1-20 The use according to claim 1, which is a straight-chain or branched alkyl having a C atom. At least one of the compounds represented by Formula I is represented by Formulas IIa-IIg
In which R ′ is independently H or R, R ′ ″ is independently H, straight-chain or branched alkyl or alkoxy having 1 to 4 C atoms, or Heteroaryl having 5 or 6 C atoms, R ^* is independently H, linear or branched alkyl having 1 to 4 C atoms, R ^X is independently H, Linear or branched alkyl having 1 to 20 C atoms, which can be substituted by cycloalkyl having 5 to 6 C atoms or aryl having 6 to 10 C atoms, wherein The aryl group may be substituted by a linear or branched alkyl or alkoxy group having 1 to 4 C atoms or by a heteroaryl having 5 or 6 C atoms, and R is As defined by claim 1 There is wherein at least one compound of formula I has the formula IIIa~IIId
And wherein X is CH ₂ , O or NR, Y is CH, N, N ⁺ R, N ⁺ —O ⁻ , and R ″ is 1 to 20 Use according to claim 2, wherein the alkyl is straight-chain or branched with C atoms, R 'is H or R, and R is defined by claim 1.   In which R is straight-chain or branched alkyl having 1 to 20 C atoms, which can be substituted by aryl having 6 to 10 C atoms, or alternatively 1 to 20 4. Use according to any one of claims 1 to 3, which is a linear or branched dialkylamino having 1 C atom. Formula I
In the formula
R ¹ , R ² and R ³ are independent of each other,
Straight-chain or branched alkyl having 1 to 20 C atoms, which can be substituted by at least one R;
An aryl having 6-10 C atoms, which can be substituted by at least one R;
Alternatively, R ¹ , R ² and R ³ are one, two or three N atoms or one N atom and one S or one O atom, and are substituted by at least one R Forming a heteroaromatic ring structure with N atoms that can be
Alternatively, R ¹ and R ² may be substituted with at least one R , with 1, 2 or 3 N atoms or 1 N atom and 1 S or 1 O atom present Forming a possible heteroalicyclic structure with N atoms, and R ³ is a linear or branched alkyl having 1 to 20 C atoms, or condensed to contain at least one N atom tricyclic structure is formed, and wherein the second or third N atom of the heterocyclic alicyclic structure or tricyclic structure -O be ^- and linear or branched having 1 to 20 C atoms Optionally substituted by alkyl
and
R is independently
Hal,
CN,
C (O) H,
Linear or branched alkyl having 1 to 20 C atoms, which is substituted by cycloalkyl having 5 to 6 C atoms or by aryl having 6 to 10 C atoms In which the aryl group may be substituted by a linear or branched alkyl or alkoxy group having 1 to 4 C atoms or by a heteroaryl having 5 or 6 C atoms,
Linear or branched alkenyl having 2 to 20 C atoms, which can be substituted by aryl having 6 to 10 C atoms, wherein the aryl group is 1 to 4 Optionally substituted by a linear or branched alkyl group having a C atom,
A cycloalkyl having 5 or 6 C atoms,
Linear or branched hydroxyalkyl having 1 to 20 C atoms,
Linear or branched alkoxy having 1 to 20 C atoms, which can be substituted by aryl having 6 to 10 C atoms,
Linear or branched alkylthio having 1 to 20 C atoms,
Aryl having 6 to 10 C atoms, wherein the aryl group is a straight chain or branched alkyl group or alkoxy group having 1 to 4 C atoms, or hetero having 5 or 6 C atoms Optionally substituted by aryl,
Heteroaryl having 5 to 10 C atoms, where the N atom of the heteroaryl group -O ^- may be substituted by,
Aryloxy having 6 to 10 C atoms,
Arylthio having 6 to 10 C atoms,
Linear or branched alkylamino or dialkylamino having 1 to 20 C atoms,
Hal is F, Cl, Br or I.
In at least one compound represented, or all of the tautomers or stereoisomers thereof, together they comprise a redox active species, the electrolyte formulation of the dye sensitized solar cell. Wherein R in at least one compound of formula I ¹ , R ² And R ³ Is a heteroaromatic ring structure in which there are 1, 2 or 3 N atoms or 1 N and 1 S or 1 O atom, which can be substituted by at least one R Formed with atoms, or R ¹ And R ² Is a heteroalicyclic structure in which there are 1, 2 or 3 N atoms or 1 N atom and 1 S or 1 O atom, which can be substituted by at least one R Together with N atom and R ³ 6. The electrolyte formulation of claim 5, wherein is a straight chain or branched alkyl having 1 to 20 C atoms. At least one of the compounds represented by Formula I is represented by Formulas IIa-IIg
In which R ′ is independently H or R, R ′ ″ is independently H, straight-chain or branched alkyl or alkoxy having 1 to 4 C atoms, or A heteroaryl having 5 or 6 C atoms, R ^* Are independently H, straight-chain or branched alkyl having 1 to 4 C atoms, and R ^X Is independently H, linear or branched alkyl having 1 to 20 C atoms, which is substituted by cycloalkyl having 5 to 6 C atoms or aryl having 6 to 10 C atoms Wherein the aryl group is substituted by a linear or branched alkyl or alkoxy group having 1 to 4 C atoms or by a heteroaryl having 5 or 6 C atoms. And R is defined by claim 5, or
Wherein at least one compound of formula I is of formula IIIa-IIId
And X is CH. ₂ , O or NR and Y is CH, N, N ⁺ R, N ⁺ -O ⁻ Wherein R ″ is a linear or branched alkyl having 1 to 20 C atoms, R ′ is H or R, and R is defined by claim 5. The electrolyte formulation as described. In which R is straight-chain or branched alkyl having 1 to 20 C atoms, which can be substituted by aryl having 6 to 10 C atoms, or alternatively 1 to 20 Electrolyte formulation according to any one of claims 5 to 7, which is a straight-chain or branched dialkylamino having 1 C atom. The electrolyte formulation according to any one of claims 5 to 8, wherein the redox active species is a redox couple of iodine and at least one iodide salt. Electrolyte formulation according to any one of claims 5 to 9 , comprising at least one compound of the formula I in a concentration of 0.01 to 30% by weight. Formula I
In the formula
R ¹ , R ² and R ³ are independent of each other,
Straight-chain or branched alkyl having 1 to 20 C atoms, which can be substituted by at least one R;
An aryl having 6-10 C atoms, which can be substituted by at least one R;
Alternatively, R ¹ , R ² and R ³ are one, two or three N atoms or one N atom and one S or one O atom, and are substituted by at least one R Forming a heteroaromatic ring structure with N atoms that can be
Alternatively, R ¹ and R ² may be substituted with at least one R , with 1, 2 or 3 N atoms or 1 N atom and 1 S or 1 O atom present Forming a possible heteroalicyclic structure with N atoms, and R ³ is a linear or branched alkyl having 1 to 20 C atoms, or condensed to contain at least one N atom tricyclic structure is formed, and wherein the second or third N atom of the heterocyclic alicyclic structure or tricyclic structure -O be ^- and linear or branched having 1 to 20 C atoms Optionally substituted by alkyl
and
R is independently
Hal,
CN,
C (O) H,
Linear or branched alkyl having 1 to 20 C atoms, which is substituted by cycloalkyl having 5 to 6 C atoms or by aryl having 6 to 10 C atoms In which the aryl group may be substituted by a linear or branched alkyl or alkoxy group having 1 to 4 C atoms or by a heteroaryl having 5 or 6 C atoms,
Linear or branched alkenyl having 2 to 20 C atoms, which can be substituted by aryl having 6 to 10 C atoms, wherein the aryl group is 1 to 4 Optionally substituted by a linear or branched alkyl group having a C atom,
A cycloalkyl having 5 or 6 C atoms,
Linear or branched hydroxyalkyl having 1 to 20 C atoms,
Linear or branched alkoxy having 1 to 20 C atoms, which can be substituted by aryl having 6 to 10 C atoms,
Linear or branched alkylthio having 1 to 20 C atoms,
Aryl having 6 to 10 C atoms, wherein the aryl group is a straight chain or branched alkyl group or alkoxy group having 1 to 4 C atoms, or hetero having 5 or 6 C atoms Optionally substituted by aryl,
Heteroaryl having 5 to 10 C atoms, where the N atom of the heteroaryl group -O ^- may be substituted by,
Aryloxy having 6 to 10 C atoms,
Arylthio having 6 to 10 C atoms,
Linear or branched alkylamino or dialkylamino having 1 to 20 C atoms,
Hal is F, Cl, Br or I.
A dye-sensitized solar cell comprising a dye-sensitized electrode containing at least one compound represented by the formula: or a tautomer or stereoisomer thereof . The dye-sensitized solar cell according to claim 11 , wherein at least one compound represented by formula I is contained in the electrolyte solution. Formula IId
Where R ′ is H,
R ^X is independently straight or branched alkyl having 6 to 20 C atoms or straight or branched alkyl having 1 to 20 C atoms, which is 5 to 6 C Substituted by cycloalkyl having atoms or aryl having 6 to 10 C atoms, wherein the aryl group is substituted by a linear or branched alkyl group or alkoxy group having 1 to 4 C atoms or 5 Or can be substituted by a heteroaryl having 6 C atoms,
Where phenylmethyl is excluded for R ^x ,
A compound represented by 14. A process for the preparation of a compound of formula IId according to claim 13 , comprising a) alkylating 2-nitroaniline to give a compound of formula IV
Wherein R ^x is defined by claim 13 ;
And b) formylation of the compound of formula IV to form intermediate V
Wherein R ^x is defined by claim 13 and then the cyclization reaction forms a compound of formula IId.